I modeled a complete new scene from scratch and I get similar results.I included also a new-style glass model (with volume precedence) which looks correct in LuxCore.

Left glass is old-style, right one uses new-style volume precedence.The lighting is different because in Classic apparently it does not work to set both efficacy and power to 0 to control the light via gain only and get reasonable brightness, so I just hacked it together.

I love how those glasses look. Basically a simple model, and such great results.

Edit: Just for comparison, here's what LuxCore Microkernel BiasPathOCL gives on the last scene (some clamping is on, so colors/brightness may differ, resolution also dec from 60 to 50% as path is in a serious disadvantage to bidir)

Biased path is a tile based render engine. I think, it only stores the data for the current rendered tile in GPU memory. For path renderer the data for the whole image has to be stored in GPU memory. Dade, correct me if I am wrong.

Biaspath definitely uses less memory, and the most affecting factors are tile resolution and AA samples.

I would also like to add that with Metropolis, there is a larger memory requirement than for e.g. Sobol when increasing path depths. That is, if you set a large path depth on Metropolis you need a large amount of memory, where with Sobol you can set anything you like without impact, from my experience, I can't claim anything as I'm not sure how they work internally. I think that in biaspath also path depth doesn't have much effect on memory (likely related to sampler used), but AA settings do affect memory usage and GPU saturation a lot, still if the tile size is smaller, you have more space to increase this.

So, it's worth also trying Sobol if you want a large path depth without too much memory consumption, to avoid such errors.

Another thing you can do to reduce memory on PathOCL regardless of sampler is send less data to each device. This can slow things down less or more depending on device, but will reduce memory usage, sometimes significantly.

In the custom luxcore commands field, write:opencl.task.count = 64000If still an error, try:opencl.task.count=32000